U.S. patent application number 11/992282 was filed with the patent office on 2009-07-09 for method for augmenting a network.
This patent application is currently assigned to Nokia Siemens Networks GmbH & Co. KG. Invention is credited to Michael Frantz, Alexandra Ribeiro.
Application Number | 20090175202 11/992282 |
Document ID | / |
Family ID | 35457793 |
Filed Date | 2009-07-09 |
United States Patent
Application |
20090175202 |
Kind Code |
A1 |
Ribeiro; Alexandra ; et
al. |
July 9, 2009 |
Method for Augmenting a Network
Abstract
To augment a network by adding a network element, network
services affected by the augmentation, and a temporary route for
transmitting network services determined as affected by the
augmentation via the temporary route are determined. A new route
through the augmented network, and a spanning tree corresponding to
the new route are determined. Memberships of a virtual local area
network (VLAN) in ports of network elements of the temporary route
are configured. Cost factors at these ports are changed such as to
direct the network services determined as affected by the
augmentation through the temporary route. A VLAN membership is
calculated for each port in the new route for a network service
that passes through the augmented network. The new route through
the augmented network is re-calculated based on the spanning tree,
and VLAN memberships in the ports of network elements which are no
longer needed are deleted.
Inventors: |
Ribeiro; Alexandra;
(Alverca, PT) ; Frantz; Michael; (Munchen,
DE) |
Correspondence
Address: |
K&L Gates LLP
P.O. BOX 1135
CHICAGO
IL
60690
US
|
Assignee: |
Nokia Siemens Networks GmbH &
Co. KG
Munich
DE
|
Family ID: |
35457793 |
Appl. No.: |
11/992282 |
Filed: |
August 23, 2006 |
PCT Filed: |
August 23, 2006 |
PCT NO: |
PCT/EP2006/008248 |
371 Date: |
March 19, 2008 |
Current U.S.
Class: |
370/256 |
Current CPC
Class: |
H04L 12/462 20130101;
H04L 12/4679 20130101; H04L 45/28 20130101; H04L 45/22 20130101;
H04L 45/00 20130101; H04L 41/12 20130101 |
Class at
Publication: |
370/256 |
International
Class: |
H04L 12/28 20060101
H04L012/28 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2005 |
EP |
05020776.0 |
Claims
1.-6. (canceled)
7. A method for augmenting a telecommunications network by adding a
network element to an existing network, comprising: determining
network services affected by the augmentation; determining a
temporary route for transmitting network services determined as
affected by the augmentation via the temporary route; determining a
new route through the augmented network; determining a spanning
tree corresponding to the new route for the network services
determined as affected by the augmentation; configuring memberships
of a virtual local area network (VLAN) in ports of network elements
of the temporary route; changing cost factors at these ports such
as to direct, based on the changed cost factors, the network
services determined as affected by the augmentation through the
temporary route; calculating a VLAN membership for each port in the
new route for a network service that passes through the augmented
network; re-calculating the new route through the augmented network
based on the spanning tree determined for the new route; and
deleting VLAN memberships in the ports of network elements which
are no longer needed.
8. The method of claim 7, wherein the new route corresponds to the
temporary route.
9. The method of claim 7, wherein the new route corresponds to a
route including the added network element.
10. The method of claim 9, wherein a VLAN membership is configured
in the new network resources for the added network element.
11. The method of claim 10, wherein VLAN memberships for ports of
the temporary route are deleted.
12. The method of claim 11, wherein a plurality of temporary routes
is determined by employing a Multiple Spanning Tree Protocol.
13. The method of claim 7, further comprising adding bandwidth
requirements for each port for which a VLAN membership is
calculated.
14. The method of claim 7, further comprising calculating
alternative routes to the new route.
15. The method of claim 7, wherein the network augmentation is
performed in an Ethernet network.
16. The method of claim 7, wherein the network services comprise at
least one of Voice over IP, Streaming Video, and Video on Demand.
Description
[0001] A method for augmenting a telecommunications network, in
particular an Ethernet network, is described.
[0002] Similar to SDH (Synchronous Digital Hierarchy) and ATM
(Asynchronous Transfer Mode) Networks, high service reliability is
also desired for Carrier Grade Ethernet Networks. For this, the
capacity of the Ethernet network is managed in a management system
to avoid overbooking for services with guaranteed traffic. Each
service has a bandwidth, and one or several dedicated routes may be
assigned for the service. The several dedicated routes may include
one active route and optional n protective routes. The protected
routes are enabled in the case where the active route is disrupted.
The management system ensures that the capacities of the network
resources used for services with a Class of Service "CoS", which
indicates a certain amount of guaranteed bandwidth, are not
overbooked.
[0003] In many cases it may be necessary to add a network element
to an existing network, a procedure called network augmentation.
This can lead to traffic disruption, since the new network element
might change the network's topology and therefore break the
connectivity to already established services. Thus, a network may
suffer prolonged downtime.
[0004] A "service" is understood to be an object in a management
system, which realises a service for a subscriber. Correspondingly,
a service can represent a means for implementing an offer made by a
provider to a subscriber. Each service with a CoS with guaranteed
bandwidth is assigned the bandwidth required for the desired data
transmission. Examples of services would include be VoIP (Voice
over IP), Streaming Video or Video on Demand.
[0005] A "network resource" is understood to be a means for
transmitting data across a network. A network resource would thus
include network elements and links.
[0006] An example of a "network element" is a network card or a
workstation. A "link" is understood to be a physical or logical
connection between 2 ports of the same or different network
elements.
[0007] A "route" is a path for data transmission that includes at
least one link and connects one network element to another.
[0008] An "active route" is considered to be a route in a network
that is not disrupted. It can be the route of the service through a
spanning tree, whereby the spanning tree is created by switching
network elements together according to STP, the Spanning Tree
Protocol. This is a protocol which enables rerouting of network
traffic when a link is disrupted or a network element is
defective.
[0009] One goal to be achieved lies in finding a method whereby a
telecommunications network is not disrupted or at least minimally
disrupted when being augmented.
[0010] One method for augmenting a telecommunications network which
achieves this goal lies in: [0011] preparing the augmentation by:
[0012] determining the services which would be interrupted due to
the addition of a network element to a current network, [0013]
determining a temporary route around the at least one affected
service, [0014] defining a new route by identifying the ports of at
least one new network element to be added to the current network
and by identifying the ports of the network elements to be
connected to the new network element, [0015] physically augmenting
the network by: [0016] enabling the temporary route, [0017] adding
the new network element physically to the current network, thus
creating a physically augmented network, [0018] disabling the
temporary route, [0019] enabling the new route.
[0020] The method has the advantage in that a service can be
rapidly reconfigured when an existing network is augmented by a new
network element, thus saving time, work and cost and reducing the
downtime of a network during the physical augmentation process.
Traffic interruption can be reduced at least to the time period
required by a re-rerouting program re-route the traffic, in
particular one based on STP.
[0021] It is preferred that the ports of the new network element
and the ports of the network elements connected to the new network
element, which during the augmentation were disrupted, are given
VLAN assignments.
[0022] A "VLAN" is a Virtual Local Area Network and includes a
logical connection of a plurality network elements connected by
links. A VLAN may be assigned a specific network address, such as a
MAC (media Access Control) Address. The ports of network elements
may be assigned to one or more VLANs, thus enabling traffic to be
directed to certain VLANs within a network.
[0023] It is preferred that the physical addition of the new
network element is detected electronically. Thus, a reconfiguration
of the resources affected by the augmentation can be triggered by
electronic notifications for an element manager.
[0024] If the new route is determined with the use of the Spanning
Tree Protocol, the advantage arises that manually searching through
a usually complex network for an alternative route is not
necessary.
[0025] In a preferred variation of the method, the temporary route
may be chosen to be an alternative route in a network. This may be
an alternative route in a protected network. The temporary route is
preferably enabled at the latest when the augmentation process is
physically being carried out, and preferably disabled after the
newly introduced network elements have been given network
addresses, which may comprise VLAN assignments.
[0026] In yet another preferred extension of the method, a network
is used for the augmentation which includes an Ethernet
Network.
[0027] The described methods are further explained by means of the
following examples and drawings, whereby:
[0028] Drawings 1a, 1b show a network in an augmentation process
whereby a new network element is inserted between two existing
ones,
[0029] Drawings 2a, 2b show how two existing network elements are
connected with an additional new network element,
[0030] Drawing 3 shows a network in which an alternative route is
found around an existing route,
[0031] Drawing 4 shows an alternative route determined for an
augmented network topology,
[0032] Drawing 5 shows protecting routes added to the network by
means of configuring of a VLAN in the additional ports of the
alternate routes.
[0033] Drawing 6 shows a current network topology with an active
route,
[0034] Drawing 7 shows a current network topology, whereby ports of
network elements are given new assignments,
[0035] Drawing 8 shows a current network topology with an activated
alternative route, whereby cost factors have been changed,
[0036] Drawing 9a shows a current network topology when an active
route determined by a spanning tree and an alternative route,
[0037] Drawing 9b shows an augmented network topology in which VLAN
assignments of ports not part of a new route are deleted,
[0038] Drawing 10a shows a current network topology in which an
active route determined by a spanning tree, an alternative route
and a projected active route for an augmented network,
[0039] Drawing 10b shows an augmented network topology in which
VLAN assignments are added in ports of the new resources and
deleted in ports which are not part of the new route,
[0040] Drawing 11a shows a current network topology with an active
route, an alternate route and a projected active route in an
augmented network
[0041] Drawing 11b shows an augmented network topology in which
VLAN assignments are added in ports of the new resources and
deleted in ports which are not part of the new route,
[0042] Referring to Drawings 1a and 1b, a new network element nNE
is inserted into a link L1 that is assigned to transmit traffic and
may be transmitting traffic. In this case, the link L1 between the
two network elements NE1 and NE2 must be deleted, and two new links
may be created, which connect the new network element nNE to the
formerly connected network elements. These two new links L2 and L3
create an alternative route AR. During the time the old link L1 is
removed and the new network element nNE is installed and
configured, the services transmitted via the old link which was
removed will be interrupted until all services are reconfigured for
the augmented network topology which includes the new network
element nNE. Drawing 1b shows the state where the new network
element has been inserted into a path between network elements NE1
and NE2.
[0043] Referring to Drawings 2a and 2b, a new network element nNE
is added with two new links L2 and L3, connecting it to two already
present network elements NE1 and NE2. In this example, no existing
links, such as the link L1 connecting network elements NE1 and NE2,
are directly affected by the addition of the new network element
nNE since a programmed device or an operator is merely creating new
links L2 and L3. However, when STP is applied, a previously
existing link, such as the link L1, may be disabled, causing
services that pass through it to be interrupted until all affected
services are reconfigured for the augmented network topology with
the added new network element nNE.
[0044] It is possible to prevent a disruption of a network during
augmentation by carrying out the following method: [0045] 1.
Determine which services will be affected by the network
augmentation. This can be achieved by keeping a database on a
network management system that stores all the services that the
operator configured in its database. Thus, when a link is changed
by a network augmentation operation, the affected services may be
determined merely by checking the database to see which services
pass through the affected link(s). The network augmentation effects
on the network can be predicted or simulated with a testing device,
on which an appropriate program can be mounted. [0046] 2. If the
service is unprotected, i.e., if it does not have an alternative
route such as the one designated by AR in Drawing 1, then determine
new alternative routes in the current network. This involves
determining the route of the spanning tree if the network resources
which are affected by the augmentation are not available. [0047] 3.
Determine the alternative routes in the augmented network for all
services identified in step 1. This involves determining the route
of the spanning tree if the network resources are available. The
calculation of the spanning trees in this step and in step 2 may
require detailed knowledge of all cost factors configured in the
network. A cost factor may, for example, include bandwidth
reservations for the links in the network. [0048] 4. Add a desired
VLAN membership to all ports for both alternative routes, i.e., for
the alternative routes before and after augmentation, for all
services. If the service already has alternative routes, this step
need be carried out only for the augmented network. [0049] 5. Store
all services which have been modified for later adoption.
[0050] After the network has been augmented, the new route for the
spanning tree must be evaluated. Then the effects on the services
modified are preferably be analysed, after which all alternative
routes may be deleted.
[0051] Although this process is thorough, it may be time consuming,
in particular for complex networks.
[0052] Thus, an augmentation procedure as follows is preferred.
[0053] A network is first prepared, so that services will not be or
will only minimally be affected when the augmentation procedure
begins.
[0054] For the preparation, an operator or a programmed device
enters the concerned network resources in the existing network
topology and defines the augmented network topology with the
resources. This state of augmentation can be considered to be a
planned, as opposed to a physical, state. More specifically,
planned network elements, links, cards or cost factors are added
into the network topology. It is at this stage possible to either
augment the network based on the spanning tree which is defined by
the current cost factors or reconfigure the spanning tree, that is,
to change the cost factors.
[0055] After the existing (current) topology has been augmented
with the so-called planned elements, the following steps can be
executed by a system governing the augmentation operation, such as
a programmed product controlling a computer device or a controlling
circuit, to prepare the network augmentation in dependence on the
spanning tree which is chosen as suitable.
[0056] If the augmentation is to be performed based on the current
cost factors configured in the network, protection of the network,
that is, prevention of traffic loss, is preferably achieved
according to the following method: [0057] A1). The services which
would be interrupted for a special network augmentation scenario
are determined by the system. The found services can be assigned to
a network augmentation process and given labels defined by the
program or operator. [0058] A2). Should the service not have
protection, i.e. no alternative routes had already been calculated
and provisioned, new alternative routes of the service for the
current network topology are determined. These alternative routes
can be dependent on the current spanning tree for the network
resources which will not be available during the augmentation
process for all services that have been identified as being
affected by the augmentation process. The network at this stage is
not augmented yet. [0059] A3). Determining an alternative route for
the augmented network topology and the augmented spanning tree
(augmented network) for the services that have been identified as
being affected by the augmentation process. [0060] A4). For the
services that have been identified as being affected by the
augmentation process, the alternative, protecting routes, which in
steps b). and c). could be the same, are added by the configuration
of a VLAN in the additional ports of the alternative routes.
[0061] Drawing 3 shows step A2 graphically. The dashed line in the
drawing shows an active route actR passing through a nominal,
undisrupted path in a current network topology. The dotted line
shows an alternative route AR in the current network, which was
determined as the network had no protected route. The alternative
route AR is dependent on a spanning tree protocol which is suitable
for finding alternative routes by switching the appropriate network
elements in a network.
[0062] Drawing 4 shows step A3 graphically. The dashed line in the
drawing represents the active route actR in the augmented network
topology whereas the dashed/dotted lined shows the alternative
route AR in the augmented network. Due to the addition of the new
network element nNE, an alternative route now passes through the
added network element nNE. Thus, the number of network elements
through which the data passes from network elements NE1 and NE2,
formerly only the one network element NE3, has now been increased
to two, as the data now passed through network elements NE3 and
nNE.
[0063] Drawing 5 shows step A4 graphically. Here, VLAN assignments
have been given to all additional ports of the network elements
NE1, NE2 and NE3. Thus, additional ports comprise all ports of the
newly added network element and the ports of the old network
elements that are newly connected to the new network element. The
dashed/dotted line represents the projected active route actRa in
the augmented network and the dotted line the alternative route AR
in the current network.
[0064] If, however, the augmentation is to be performed based on
changed cost factors in the network, the network traffic is
re-routed to ensure service ability. Whereas in the case where no
changes are made or required it is possible to differentiate
between the services which shall not be affected by the network
augmentation based on the traffic class, according this method all
services are handled equally. The augmentation is performed as
follows: [0065] B1). The services which would be interrupted for a
particular network augmentation scenario are determined by the
system. The found services can be assigned to a network
augmentation process, whose label is definable by the program or
operator. [0066] B2). The system determines a different route as
well as the corresponding cost factors to enable that all traffic
traversing the network resources affected by the network
augmentation scenario is transmitted via a different route. If an
MSTI (Multiple Spanning Tree Instance) is present in the network, a
plurality of different routes as well as the corresponding cost
factors are determined by the system is determined to enable that
all traffic as above is in this case transmitted via a plurality of
different routes. [0067] B3). The route(s) of the augmented
topology and the augmented spanning tree for the services
identified in Step B1 is determined. This route may be the same as
the one found in step B2. [0068] B4). For the services found in
step B1, the new routes, which could be the same as the ones in
steps B2 and B3, are added by the configuration of VLAN in the
additional ports of the new routes. [0069] B5). The cost factor is
changed in the network according the results of step B2. With this,
all the traffic traversing the network resources affected by the
network augmentation are automatically re-routed. As a result, no
traffic is transmitted via the network resources which are affected
by the network augmentation.
[0070] Drawing 6 can be referred to step B1 and shows the basic
situation where a current network topology with an active route
actR, indicated by the dashed line, connecting at least network
elements NE1 and NE2, is about to be augmented. The service which
would be interrupted by an augmentation is a service that runs
through network elements NE1 and NE2. This service can be labelled
for later retrieval after the physical augmentation has carried
out.
[0071] Drawing 7 may be referred to step B4 and shows a current
network topology in which VLAN assignments are added to the ports
of the new resources of an augmented network, i.e. those resources
which will connect the links of a new route in the augmented
network. The dashed line indicates an active route and the dotted
line a new route, which however is not yet configured in the new
network.
[0072] Drawing 8 shows step B5 graphically, whereby a current
network topology is presented. The active route is indicated by the
dashed line and is reconfigured to pass through network element
NE3. The arrows pointing to the ports of the network elements NE1
to NE3 indicate a change in cost factors of .DELTA.cf brought about
by the change in route.
[0073] After the preparatory stage as described, the network may be
augmented by the programmed device or operator. The network may be
altered physically by replacing a network element or adding another
network element to the existing topology. For example, a network
card could be automatically replaced or inserted into a network
with the help of a machine. Physical modifications to the network
may however not be visible to the network management system.
[0074] When the network topology has been physically changed, the
new or deleted network resource can be entered, for example by
adding or deleting new network elements or links. The system is
alternatively programmed to electronically detect the changes that
have been made to the network due to object creation or deletion.
This may the new case when a network card has been added or
removed. The system may analyse notifications from the element
managers to ascertain which changed occurred in the network.
[0075] After the augmented topology is defined in a management
system as a preparatory measure, all services identified as being
affected by the augmentation can automatically be adopted to the
augmented network. For this, the new augmented network topology, as
well as the new spanning tree (which defines the new routes, active
or protected) are analysed and adopted automatically to the new
network topology, preferably including the reconfiguration of the
corresponding VLAN settings in the network, for all services
concerned by the augmentation process. Thus, the routes of the
services are recalculated and, if it is a CoS, its bandwidth
allocation along the path. The path recalculation involves the
following steps: [0076] Re-determining the service's path based on
the new spanning tree. [0077] after re-determination of the service
path, the correct VLAN membership is set for each port the service
goes through, whereby the following scenarios are distinguished:
[0078] a. One of the routes calculated in steps A2 or B2 and the
route in step A3 or B3 are identical. In this case, the system
deletes the VLANs at the ports of the old routes for the resources
which are no longer needed, assuming that the service shall not be
protected. If the service is protected, these VLANs remain at the
ports to which the routes are connected. [0079] b. The new route
equals the route determined in step A3 or B3. In this case the
VLANs are deleted at the ports of the old route for the resources
which are no longer needed, as well as for the alternative route,
which is the route calculated in steps A2 or B2. This assumes,
however, that the service will not be protected. [0080] c. The new
route equals the old route with the new network resources added. In
this case the services are interrupted due to the missing VLAN
configuration in the new augmented network resources. To minimise
the time for the interruption, it is preferred that the gap is
detected, i.e. the missing VLAN configurations, and configures the
VLAN membership in the new resources for all services to be
adopted.
[0081] Drawings 9a and 9b may be referred to step a. as delineated
above and show a current network topology and an augmented network
topology, respectively. The dashed line shows an active route
determined by a spanning tree protocol and the dotted line an
alternative route. In Drawing 9b, the arrows pointing to the ports
of NE1 and NE2 which are connected with the new network element nNE
indicate a deletion of a VLAN assignment (VLAN-), as these ports
are not part of the alternative and temporary route AR. Thus,
traffic can temporarily only pass through the alternate route which
passes through NE3. However, since the new network element will be
a member in the augmented state, VLANs are assigned to its ports
(VLAN+), so that the new network element will be prepared when the
assignment of the ports deleted for NE1 and NE2 is
re-introduced.
[0082] Drawings 10a and 10b present a current network topology and
an augmented network topology and may be referred to step b. The
active route actR is indicated by a dashed line. The dotted line
indicates an alternative route AR in the not yet augmented network.
The dashed/dotted line indicates the active route actRa in the
augmented network. It can be seen that the active route in the
augmented network passed through network element NE1, then NE3 and
then NE2. The alternative route (dotted line), which is temporarily
enabled to prevent traffic disruption, avoids taking the path of
the current active route AR, which would be disrupted when new
network element nNE is added. Drawing 10b shows the deletion and
addition of VLAN assignments to the ports of the network elements
that are affected by an augmentation. For new network element nNE,
VLAN assignments are added to each port (VLAN+). For the old
network elements NE1 to NE3, the VLAN assignments in the ports
which are not part of the new route are deleted (VLAN-).
[0083] Drawings 11a and 11b may be referred to step c. and shows a
current and an augmented network topology, respectively. Drawing
11a shows how an active route actR (dashed line) in the augmented
network is configured to pass straight through network elements
NE1, nNE and NE2. This route corresponds to the old active route.
Since the appropriate VLAN configurations are missing, however, the
service between NE1 and NE2 via nNE3 will be interrupted. The gap
can be detected and the missing VLAN configurations to each of the
concerned network elements carried out. This is shown in drawing
11b.
[0084] For every determination of a new route, the need for an
accompanying, protected route is considered. Thus, the service's
alternative routes are re-determined.
[0085] The determination of the new VLAN connections includes
evaluating the bandwidth requirements for each link. If extensive
modifications have been made to a service's path, then new
bandwidth reservations are made at new ports, whilst erasing the
previous ones. This may be done in several steps for each service:
[0086] Identifying the network elements and links which are no
longer present in the service due to the changes in the network
topology. [0087] Removing all the bandwidth reserved for this
service in the previously identified network elements. [0088]
Identifying the new network elements and links in the service.
[0089] Reserving the necessary bandwidth in the previously
identified network elements.
[0090] It is preferred that the above steps are performed with
pauses in between. This way, a programmed device or an operator may
control the augmentation process by confirming the correct
execution of each step. Further, between the pauses alternative
arguments can be introduced into the process.
LIST OF ABBREVIATIONS
[0091] NE1 to NE3 network elements nNE new network element to be
inserted into network L1 to L3 links actR active route AR
alternative route actRa active route in augmented network ARa
alternative route in augmented network VLAN+ addition of VLAN
assignment VLAN- deletion of VLAN assignment
* * * * *